St John's Wort

Studies show it helps relieve mild depression, but can you be confident the brand you buy will work?
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  • Updated:13 May 2005

03.A place for St. John's Wort?

It's likely that a large number of the people being prescribed antidepressants could benefit from those SJW preparations that are backed up by good evidence for clinical effectiveness. Obviously if the TGA and manufacturers work together to ensure all products available on the shelves are good-quality, effective preparations, this will make things a lot easier for consumers and health professionals.

Benefits of SJW vs drugs include similar efficacy, lower cost (to the individual and the health system), fewer side effects and less risk of dependence. One of the main problems with conventional antidepressants for people with mild depression is that the side effects can reduce the likelihood of sticking with them.

However, simply swapping a conventional medicine for a herbal one doesn't resolve the 'pill for every ill' mentality, and doesn't provide a long-term solution, which is likely to involve making changes to thought patterns and life circumstances, and learning to deal with crises.

Ideally, perhaps, anyone suffering from mild depression would have access to whatever treatment was judged most appropriate, whether counselling, psychological therapies or medication (conventional or SJW) - alone or in combination. The reality, however, is that the provision of resources required for counselling and psychological therapies is inadequate, and for many people medication will be the primary treatment.

There are concerns about interactions of St John's wort with other medications, especially for people who self-medicate with SJW without their doctor's knowledge. But as long as you make your doctor aware of all medications (herbal and conventional) you're taking, most people can use it safely.

Chemical conundrums

Various chemicals in SJW have been found to show biological activity, and any or all of these may play a role in the antidepressant effect. The main chemicals include hypericin, pseudohypericin and other hypericins; hyperforin; and various flavonoids. SJW products have the amount of total hypericins listed on the label, and sometimes the amount of hyperforin.

The antidepressant effect was originally thought to be related to levels of hypericin, and more recently hyperforin, but a trial using a flavonoid-rich extract with no hypericin or hyperforin still found some antidepressant effect. This suggests that SJW's effectiveness is based on the product in its entirety, with compounds working together in a synergistic fashion.

For this reason, looking at the results of a chemical analysis to determine whether or not a product will work isn't as straightforward as for synthetic medicines like aspirin tablets, say, where a certain active ingredient can be identified and measured.

However, there's a need to ensure that the final preparation remains consistent over time, and companies standardise the extract (the SJW source material) against levels of hypericin to determine this consistency. While more isn't necessarily better in terms of effectiveness, unusually low levels indicate quality problems.

We thought it would be interesting to test some widely available SJW tablets to find out whether the products really contained the level of total hypericins stated on the label.

We used the most accurate test procedure available, called high-performance liquid chromatography (HPLC). However, it only gives the figures for hypericin and pseudohypericin. That means the figures we got weren't directly comparable with the labelled claims for total hypericins.

It's been reported that when added together, hypericin and pseudohypericin typically amount to around 60-80% of the known 'total hypericins'. The levels of hypericin and pseudohypericin per tablet that we found averaged 63% of claimed total hypercin. This is in line with what we'd expect, and none of the products tested had startlingly low levels of hypericin.

We also tried to test the tablets using the same method as manufacturers use to obtain figures for total hypericin (spectrophotometric analysis). However, the results were inconsistent, most likely because we were testing on the tablet form, which contains many ingredients, some of which may interfere with analysis. To do this sort of testing accurately would require the co-operation of the companies, so we'd know all the ingredients in the tablets (active and inactive).

So while the results using the HPLC method tend to confirm manufacturers' claims and quality assurance procedures, the fact that it doesn't match the methods they use when making their products doesn't make it at all easy to check their claims. Our experiences highlight the need for a testing procedure that allows for post-market surveillance of quality by independent bodies such as ourselves, to make sure we're getting what we think we're getting when we buy these products.


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